Remember all that snow you melted? While the water is still hot, pour it into a water bottle of choice (make sure the lid is sealed properly) and throw it in your sleeping bag just before climbing in for the night. The heat generated from the warm water will heat up the small space in your bag. Keep it close to your body and benefit even more from the heat.

Sleep with a hat on, so that heat body doesn’t escape from your head. If it is wet and snowy, air your tent out before going to sleep. Moisture inside the shelter can make it very cold. Lastly, do a routine of jumping jacks and squats outside your tent. Don’t go to bed already cold.